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Active Transport New

  1. 1. <ul><li>Sodium-Potassium pump </li></ul><ul><li>Types of molecules transport </li></ul><ul><li>Endocytosis & Exocytosis </li></ul>ACTIVE TRANSPORT
  2. 2. <ul><li>Transport proteins within the membrane must use energy (ATP) to move substances either to the inside or outside of the membrane. </li></ul><ul><li>Active transport requires the cell to spend energy, usually in the form of ATP. </li></ul><ul><li>Examples include transport of large molecules (non-lipid soluble) and the sodium-potassium pump. </li></ul>WHAT IS ACTIVE TRANSPORT?
  3. 3. <ul><li>Transport of molecules against a concentration gradient (from regions of low concentration to regions of high concentration) with the aid of proteins in the cell membrane and energy from ATP. </li></ul>
  4. 6. <ul><li>The mechanism that uses ATP energy to reset the sodium and potassium ions after transmission of a nerve impulse. </li></ul>WHAT IS SODIUM POTASSIUM PUMP?
  5. 7. SODIUM-POTASIUM PUMP: <ul><li>The sodium-potassium pump must break ATP down into ADP in order to pump sodium three ions outside the cell, while it pumps two potassium ions into the cell. </li></ul><ul><li>The ATP phosphorylates (adds a phosphate to) the membrane protein as it binds to the sodium and breaks down, and it dephosphorylates the protein as it binds with the potassium. </li></ul>
  6. 8. <ul><li>Cellular respiration must occur to add the phosphate back to ADP, thus restoring the ATP. </li></ul>
  7. 11. <ul><li>In the case of active transport, the proteins are having to move against the concentration gradient. </li></ul><ul><li>For example the sodium-potassium pump in nerve cells. Na+ is maintained at low concentrations inside the cell and K+ is at higher concentrations. </li></ul><ul><li>The reverse is the case on the outside of the cell. </li></ul><ul><li>When a nerve message is propagated, the ions pass across the membrane, thus sending the message. </li></ul>
  8. 12. <ul><li>After the message has passed, the ions must be actively transported back to their &quot;starting positions&quot; across the membrane. </li></ul><ul><li>To reset them you must pick each one up, again at an energy cost. </li></ul><ul><li>Up to one-third of the ATP used by a resting animal is used to reset the Na-K pump. </li></ul>
  9. 13. TYPES OF TRANSPORT MOLECULES: UNIPORT SYMPORT ANTIPORT Antiport transports the solute in (or out) and the co-transported solute the opposite direction. One goes in the other goes out or vice-versa. Symport transports the solute and a cotransported solute at the same time in the same direction. Uniport transports one solute at a time.
  10. 17. <ul><li>An active process of taking in something through a cell membrane, which uses energy (ATP). </li></ul><ul><li>Is the case when a molecule causes the cell membrane to bulge inward, forming a vesicle. </li></ul>ENDOCYTOSIS
  11. 19. <ul><li>The opposite of endocytosis, is also an active process. </li></ul><ul><li>Exocytosis moves material to the outside.  </li></ul><ul><li>A vesicle fuses with the plasma membrane and discharges its contents outside.  </li></ul><ul><li>This allows cells to secrete molecules. </li></ul><ul><li>The incorporation of materials from outside the cell by the formation of vesicles in the plasma membrane. </li></ul><ul><li>The vesicles surround the material so the cell can engulf it. </li></ul><ul><li>The fusion of vesicles to the plasma membrane adds membrane to the cell surface. </li></ul>EXCOCYTOSIS
  13. 23. Phagocytosis refers to the process of engulfing large particles. PHAGOCYTOSIS??
  14. 25. <ul><li>A vacuole is formed that contains the material that has been engulfed. </li></ul><ul><li>Known as cell eating. </li></ul><ul><li>Phagocytosis is the cellular process of engulfing solid particles by the cell membrane to form an internal phagosome, or &quot;food vacuole.“ </li></ul><ul><li>The phagosome is usually delivered to the lysosome, an organelle involved in the breakdown of cellular components, which fuses with the phagosome. </li></ul>
  15. 26. <ul><li>The contents are subsequently degraded and either released extracellularly via exocytosis, or released intracellularly to undergo further processing. </li></ul><ul><li>Phagocytosis is involved in the acquisition of nutrients for some cells, and in the immune system it is a major mechanism used to remove pathogens and cell debris. </li></ul>
  16. 27. <ul><li>Bacteria, dead tissue cells, and small mineral particles are all examples of objects that may be phagocytosed. </li></ul><ul><li>Phagocytosis is a specific form of endocytosis involving the vesicular internalization of solid particles, such as bacteria. </li></ul>
  17. 29. <ul><li>As in phagocytosis, a vesicle is formed which contains the molecules that were brought into the cell. </li></ul><ul><li>Vacuoles and vesicles produced by phagocytosis and pinocytosis can fuse with lysosomes (lysosomes are vesicles that contain digestive enzymes). </li></ul><ul><li>Phagocytosis and pinocytosis remove membrane from cell surface to form vacuoles that contain the engulfed material. </li></ul><ul><li>Cell drinking. </li></ul><ul><li>Pinocytosis refers to engulfing macromolecules. </li></ul><ul><li>Occur when the external fluid is engulfed. </li></ul>PINOCYTOSIS
  18. 31. <ul><li>In the process of pinocytosis the plasma membrane froms an invagination. </li></ul><ul><li>What ever substance is found within the area of invagination is brought into the cell. </li></ul><ul><li>In general this material will be dissolved in water and thus this process is also refered to as &quot;cellular drinking&quot; to indicate that liquids and material dissolved in liquids are ingested by the cell. </li></ul><ul><li>This is opposed to the ingestion of large particulate material like bacteria or other cells or cell debris. </li></ul>
  19. 33. <ul><li>Proton pumps operate both within the inner mitochondrial membranes in the electron transport system of cellular respiration, and in chloroplast membranes during photosynthesis. </li></ul>PROTON PUMP
  20. 35. <ul><li>In cotransport, one process (the Na-K pump), is coupled with movement of a molecule of sugar (glucose) out of the cell, while allowing sodium to enter through the protein. </li></ul>COTRANSPORT
  21. 37. <ul><li>Receptors help to attach molecules to the membrane before taking them in. </li></ul><ul><li>Macromolecules bind to receptors on the surface of the cell. </li></ul><ul><li>Receptors with bound macromolecules aggregate in one area and are brought into the cell by endocytosis. </li></ul>RECEPTOR MEDIATED ENDOCYTOSIS
  22. 38. <ul><li>The vesicle containing the macromolecules can release the macromolecules into the cell directly or they can be processed by chemicals contained within lysosomes after fusing with the lysosomes. </li></ul><ul><li>The vesicle (and receptors) then returns to the cell surface. </li></ul><ul><li>Receptor-mediated endocytosis occurs when the material to be transported binds to certain specific molecules in the membrane. </li></ul><ul><li>Examples include the transport of insulin and cholesterol into animal cells. </li></ul>